Telephone-exchange system



Jan. 14, 1930. E. H. CLARK 1,743,429

TELEPHONE EXCHANGE SYSTEM Filed June 2 1928 4 Sheets-Sheet l //vvE/v70/? EDGAR hf CLARK F'c/W AT TOR/V5 V E. H. CLARK TELEPHONE EXCHANGESYSTEM Jan. 14, 1930.

Filed June 27, 1928 4 Sheets-Sheet.

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Jan. 14, 1930. CLARK 1,743,429

TELEPHONE EXCHANGE SYSTEM Filed June 1928 4 Sheets-Sheet 3 *0 S R E Armmver Jan. 14, 1930. I E. H. CLARK 1,743,429

TEUEPHONE EXCHANGE SYSTEM Filed June 27, 1928 4 Sheets-Sheet 4 wvavrmEDGAR hf CL ARK AT TORA/E Y Patented Jan. 14, 1930 UNITED STATES PATENTOFFICE EDGAR H. CLARK, OF RICHMOND HILL, NEXV YORK, ASSIGNOR TO BELLTELEPHONE LABORATORIES, INCORPORATED, 011 NEW YORK, N. Y., A CORPORATIONOF NEW YORK TELEPHONE-EXCHANGE SYSTEM Application filed .Tune 27,

This invention relates to telephone exchange systems and moreparticularly to an indicating arrangement for the purpose of indicatingto an operator the number of a telephone line. The object of theinvent-ion is to economize in the apparatus required, and to enable suchindications to be transmitted over long cable loops.

In telephone exchanges of a machine switching-character, especiallyduring the period in which the exchanges are being converted from amanual operation basis to a machine switching basis, there are certainofiices which operate on a manual basis while others are equipped withselector switches and operate on a full machine switching basis. Forestablishing calls from lines in a machine switching ofiice of such anexchange to lines in a manual ofiice, it is the common practice for thesubscriber to set registers in a common sender in his oflice inaccordance with the office and line designation of the wanted line.Thereupon the sender operates selector switches to extend a connectionover an inter-office trunk from the calling line to the oiiice in whichthe wanted line terminates in accordance with the oflice designation ofthe wanted line number. The interotfice trunk extending to the manualofiice terminates in a manual connection plug. Common line numberindicating apparatus is associable at the manual ofitice with any one ofthe trunks incoming to the ofiice. As soon as the manual operator hasassociated the indicating apparatus with the trunk upon which a call isincoming the sender in the machine switching ofllce proceeds to sendcodes of impulses to the indicating apparatus to set registers thereinto record the the relay registers of the call indicator in 1928. SerialNo. 288,607.

the manual office by trains of impulses transmitted revertively from theindicator apparatus over the interoflice trunk to the sender. This isaccomplished by impulsing relays in much the same'manner in which therevertive impulses are transmitted by the commutators of selectorswitches to measure their selective movements. lVhen, for example, theimpulsing relays have sent a train of impulses corresponding to a digitof a wanted line number such as satisfies the particular registersetting in the sender for such digit, the impulsing or fundamentalcircuit is opened at the sender and impulsing for such digit ceases. Thenumber of impulses in each train thus sent is counted by a series ofcounting relays in the indicating apparatus, the count- 1ng relays inturn controlling the setting of the proper combinations of registerrelays of the indicating apparatus.

By thus transmitting trains of impulses revertively from the indicatingapparatus to the sender instead of transmitting codes of impulses ofspecial character from the sender to the indicating apparatus asheretofore done, since the impulses thus revertively sent are of thesame character and cause the sender to function in the same manner as incontrolling selector switches, it is possible to eliminate from eachsender the special code impulsing switch and associated circuits,thereby effecting a considerable economy in the senders. Thus not onlyis an economy of apparatus attained, but also due to the character ofimpulses used it is possible to accurately operate over long interotticecable loops.

The drawings with Fig. 1 placed above Fig. 2, Fig. 3 at the right ofFig. 2 and Fig. 4 above Fig. 3 diagrammatically represent a portion of atelephone system employing the present invention. Fig. 1 shows a callingsubscribers substation and line, the diagram matic representation of thebrushes ofa line switch. district selector. ofiice selector and centralofiice sender, an interoffice trunk terminating in a plug at the Boperators position of a terminating manual ofiice, and the substationand line of a called subscriber. Fig. 2 shows the control apparatus of aline number indicating mechanism common to the interofiice trunksincoming to the B operators position. Fig. 3 shows the lamps andcontrolling relays for indicating the tens, units and stations digits ofwanted line numbers. Fig. 4 shows the lamps and controlling relays forindicating the thousands and hundreds digits of line numbers.

For the purpose of this disclosure the apparatus of the originating dialswitching ofiice of Fig. 1 has been abbreviated, but it may be of thecharacter fully disclosed in the patent to F. A. Stearn No. 1,505,171,granted August 19, 1924. The trunk circuit terminating at the manualoflice disclosed in the right portion of Fig. 1 and the number indicating apparatus disclosed in Figs. 2, 3 and 4 is in general of thesame character as disclosed in the patent to A. E. Lundell and E. H.Clark No. 1,464,084, granted August- 7, 1923, modified, however, inaccordance with the present invention.

It is believed that the invention will be best understood through adetailed description of the manner in which a connection is establishedfrom the line of the calling substation 100 terminating in theoriginating dial switching oflice to the line of substation 150terminating in a manual ofiice. WVhen the calling subscriber removes hisreceiver from the switchhook, the line switch 101 in which his lineterminates hunts for and connects with an idle district selector trunk102 which, in turn, becomes connected in the well-known manner with anidle register sender 103. As soon as an idle sender is selected thecalling subscriber receives a dialing tone and commences to dial theoffice code and numerical digits of the wanted line number, therebysetting registers of the sender to record those digits. After the officecode digits have been recorded, the sender 103 proceeds to operate thedistrict selector 104 and the ofiice selector 105 to extend the callingline to an idle interoflice trunk 106 terminating in a connection plug107 before a B operators position in the terminating office in which thedesired -line terminates.

Upon the seizure of trunk 106 a circuit is established from batterythrough the lower winding of relay 108, the right normal contacts ofrelay 109, the upper back contact of relay 110, the tip brushes ofselectors 105 and 104, the lower contact of earn 112 to the sender 103,returning over the upper contact of cam 111, the ring brushes ofselectors 104 and 105, the lower back contact of relay 110, the leftnormal contacts of relay 109 to ground through the upper winding ofrelay 108. Relay 108 operates and closes a circuit for relay 113extending from ground at the contact of relay 108, the left back contactof relay 114, winding of relay 113 to battery at the inner back contactof relay 115. Relay 113 operates and at its inner right front contactcloses a locking circuit for itself directly to battery independent ofrelay 115, and at its outer right front contact closes an obviouscircuit for the lamp 116, the illumination of which notifies theoperator that a connection has been extended to the trunk 106 from adistant dial switching office.

In response to the illumination of lamp 116 the operator actuates theassignment key 117 individual to the trunk 106 for the purpose ofassociating with the trunk, call indicator mechanism shown on Figs. 2, 3and 4 to receive the transfer of the wanted line designation from thesender 103. The depression of key 117 closes a circuit from batterythrough the winding of relay 201, conductor 202, the lowermost backcontact of relay 120, the right winding of relay 118, the left frontcontact of relay 113, the right contact of key 117, conductor 119, backcontact of relay 203 to ground at the outer back contact of relay 204. Abranch of this circuit extends through the winding of relay 205 toground, but due to the direct path to ground relay 205 cannot operate.Relays 201 and 118 become .energized and a new circuit for these relaysis established from battery through the winding of relay 201, conductor202, the lowermost back contact of relay 120, both windings of relay 118in series, inner left contact of relay 118 to ground. Relay 118establishes a circuit from ground through its right front contact, thewinding of relay 115 to battery at the intermediate lower back contactof relay 120. Relay 11.5 operates and a circuit is closed from batterythrough the inner right front contact of relay 113, the lef frontcontact of relay 115 to ground through the winding of relay 121. Relay121 energizes and closes a circuit from battery through the winning ofrelay 114, the right front contact of relay 121 to ground through thewinding of relay 121. Relay 114 does not energize since its winding isshunted by the circuit from battery through the inner right frontcontact of relay 113 and the left front contact of relay 115. Relay 121also closes a circuit from battery over its left contact, the winding ofrelay 110, outer left contact of relay 118, conductor 122, winding ofrelay 203 to ground at the inner back contact of relay 204. Relays 110and 203 become energized. Relay 203 opens the shunt around the windingof relay 205, previously mentioned, but relay 205 re mains deenergizedsince the circuit thereof is opened at the right contacts of key 117 assoonv as the operator releases such key.

lVhen relay 110 energizes it opens the circuit extending to the sender103 through the windings of relay 108. Relay 108 opens the circuit ofrelay 113 which thereupon deener gizes and removes the short circuitfrom around the winding of relay 114. Relay 114 now becomes energized inseries with relay 121 over the circuit previously traced. The

cont-act of relay 207.

release of relay 113 completes a circuit from battery through the lamp116, the right back contact of relay 113, the right front contact ofrelay 115 to ground through the interrupter 123. The lamp 116 ceases toburn steadily and instead is intermittently flashed by the constantlyrotating interrupter 123. This flashing signal will continue throughoutthe period in which the relay call indicator is being operated. Relay110 at its front contacts extends the incoming conductors of the trunk106 over conductors 124 and 125 toward the call indicator. t the senderthe circuits are prepared for transferring the numerical designation ofthe desired line to the registers of the call indicator.

Relay 201, upon energizing, also closes a circuit for advancing sequenceswitch 200 out of normal position 1 into position 2, which may be tracedfrom battery, winding of magnet 200, the upper left contact of cam 206,the outer rightcontact of relay 201 to ground at the outer right backcontact of relay 207. lVith sequence switch 200 in position 2 a circuitis closed for relay 208 extending from ground, winding of relay 20.8,the upper left contact of cam 209 to battery. Conductor 124 is nowextended over the left contact of relay 208 to battery through the winding of relay 210 and conductor 125 is extended over the right contact ofrelay 208, the lower right contact of cam 211, conductor 213, the innerright front contact of relay 201 to ground at the inner right back Relay210 and the stepping relay of the sender 103 energize in this circuitpreparatory to transferring the thousands registration from a registerof the sender 103 to a relay register of the call indicator. Relay 210,upon energizing, closes a circuit for relay 212 extending from ground onconductor 213 over the lower left contact of cam 211, the front contactof relay 210 to battery through the winding of relay 212. Relay 212locks to ground on conductor 213 over its inner left front contact, theupper contact of cam 211, and also in a circuit through its winding, thefront contact of relay 210 to ground at the outer left contact of relay212. Relay 212 alsocloses a circuit for advancing sequence switch 200into position 3 extendinig from battery through the magnet 200, thelower left contact of cam 206 to ground at the right front contact ofrelay 212. As soon as sequence switch 200 leaves position 2, the shuntwhich in position 2 extended around the winding of relay 214 over thelower contacts of cam 211' is removed and relay 214 energizes over thepulsing circuit extending to the sender 103 previously traced. Relays210 and 214 are now both energized over the pulsing circuit in serieswith the stepping relay of the sender 103.

Two circuits are now closed in parallel, one extending from battery atthe lower left contact of cam 209, over conductors 215 and 216, thewinding of the No. 9 counting relay, the back contact of the No. 9counting relay, conductor 223, contacts of cam 217 to ground at thefront contact of pulsing relay 214, and the second extending from groundat the front contact of relay 214, over the contacts of cam 218 tobattery through the winding of relay 219. Relay 219 and the No. 9counting relay both energize, the No. 9 counting relay closing a lockingcircuit for itself from battery on conductor 216, through its ownwinding and the winding of the No. 9' counting relay, the front contactof the No. 9 counting relay, conductors 220 and 221, the lower leftcontact of cam 222 to ground on conductor 213. The No. 9 counting relay,however, does not energize in this locking circuit as its winding isshunted by ground on the front contact of relay 214 as long as relay 214remains energized. Relay 219, upon energizing, connects ground at itsfront contact to the winding of relay 210 and to conductor 124 and,since conductor 125 is also connected to ground through the winding ofrelay 214 and the outer left front contact of relay 212, the steppingrelay of the sender 103 and the pulsing relay 214 become deenergized.

Relay 214 upon deenergizing removes the shunt from the winding of theNo. 9 counting relay, whereupon such relay energizes extending thecounting relay control conductor 223 over its front contact, the back,contact of the No. 8 counting relay to battery through the No. 8counting relay upon the next energization of the pulsing relay 214.Relay 214, upon deenergizing, also opens the circuit of relay 219, whichin turn deenergizes removing the shunting ground at its front contactfrom the windings of pulsing relay 214 and the stepping relay of sender103. These latter relays again energize and relay 214 now causes theoperation of the No. 8 counting relay and the reoperation of relay 219.The No. S counting relay now locks through the winding of the No. 8counting relay. In the manner just described, successive counting relaysare operated until the sender 103 is satisfied as to its thousandsregistration when the pulsing circuit will be opened in the well-knownmanner at the sender 103, opening the circuits of relays 214 and 210.Since one locking circuit of relay 212 was opened at the upper contactof cam 211 when sequence switch 200 advanced into position 3, the relay212 now deenergizes when its other locking circuit is opened at thecontact of relay 210. Relay 212 thereupon closes a circuit for advancingsequence switch 200 into'position 4, extending from battery through thewinding of magnet 200, the lower right contact of cam 206 to ground atthe right back contact of relay 212. At the sender 103 circuits areprepared for transferring the remainder of the thousands and a portionof the hundreds registration from registers therein to the callindicator. WVith sequence switch 200 in position 4, the previouslytraced pulsing circuit extending to the sender 103 through the steppingrelay thereof, and through the winding of relay 210 is againestablished.

It will be assumed that the number of the wanted subscriber is 3983-J.The originating sender 103 is not aware of the fact that the controlwhich it is to exercise in accordance with the registered designation isto be over a call indicator mechanism rather than over panel typeselector switches and therefore it proceeds as though six series ofrevertive impulses are to be received thereby from selective switches,i. e., an incoming brush series and incoming group series to satisfy thethousands digit registration and to partially satisfy the hundreds digitregistration in the sender, final brush, tens, and units series tofurther satisfy the hundreds registration and the tens and unitsregistrations, and a stations series to satisfy the stationsregistration. Thus in response to the first series of revertive impulsestransmitted to the sender 103 from the call indicator two pairs ofcounting relays No. 9 and No. 9 and No. 8 and No. 8 have been operatedand locked.

The manner in which a record of this first series of impulses is made onthe register relays 400, 405 and 410 will now be described. Vhensequence switch 200 passes into position 3 a circuit is extended frombattery, over the lower right contact of cam 209, conductor 401, bothwindings of register relay 400, conductor 402, the lower contacts of cam224, the back contact of the No. 7 counting relay, over conductor 221,the lower left contact of cam 222 to ground on conductor 213. Until theNo. 9 counting relay energizes a shunt around the right winding of relay400 exists which may be traced from the unction of the two windings ofrelay 400, over the left back contact of relay 400, conductor 403, thelower contacts of cam 225, the back contact of the No. 9 counting relayto ground on conductor 221. As soon as the No. 9 counting relayenergizes relay 400 energizes.

A circuit is also established for relay 405 extending from battery onconductor 401 through both windings of relay 405, conductor 406, thelower contacts of cam 226, the back contact of the No. 6 counting relay,to ground on conductor 221. Until the No. 8 counting relay energizesthere is a shunt around the right winding of relay 405 which may betraced from the junction of the two win-dings of relay 405, over itsleft back contact, conductor 407, the lower contacts of cam 227, theback contact of the No. 8 counting relay, to ground on conductor 221.This shunt is opened at the back contact of the No. 8 counting relaywhen that relay is energized and relay 405 thereupon energizes.

A circuit is also established for relay 410 extending from battery onconductor 401, through both windings of relay 410, conductor 408, thelower right contact of cam 228, the back contact of the No. 4 countingrelay, to ground on conductor 221. V This relay, however, does notenergize since its right winding is shunted over its outer left backcontact, conductor 409, the lower contacts of cam 229, the back contactof the No. 5 counting relay to ground on conductor 221. Since the No. 5counting relay has not been energized relay 410 cannot operate. Thus inresponse to the operation of the counting relays two register relays 400and 405 have been operated. When sequence switch 200 advances intoposition 4 locking circuits therefor are established. The lockingcircuit of relay 400 may be traced from battery on conductor 401,through both windings and the inner right contact ofrelay 400, conductor404, the lower right contact of cam 222 to ground on conductor 213. Thelocking circuit of relay 405 may be traced from battery on conductor401, through both windings and the inner right contact of relay 405,conductor 404 to ground on conductor 213.

It will be recalled that upon the termination of the first series ofimpulses, sequence switch 200 advanced into position 4 againestablishing the pulsing circuit between the sender 103 and the callindicator causing the energization of relay 210. Relay 214 is at thistime shunted at the contacts of cam 211. Relay 210 upon energizing overthe pulsing circuit again operates relay 212 which locks in the mannerbefore described and closes the previously traced circuit for advancingsequence switch 200 into position 5. The operated counting relays are atthis time released as their locking circuits were opened at the lowerleft contact of cam 222 when sequence switch 200 passed out of positionWith sequence switch 200 in position 5 the shunt around the winding ofrelay 214 is removed and this relay energizes over the pulsing circuitclosing the previously traced parallel circuits through the winding ofrelay 219 and the winding of the No. 9 counting relay.

In the manner previously described relays 214 and 219 cooperate tosuccessively operate and lock pairs of counting relays until thecounting relays of the sender 103 have been operated to satisfy thecombined thousands and hundreds registrations therein when thefundamental circuit will be opened at the sender 103 releasing relays210 and 214. The release of relay 210 in the manner previously describedopens the holding circuit of relay 212 which releases and causes theadvance of sequence switch 200 into position 6. Since it is assumed thatthe subscribers line number is 3983-J, the second series of impulsestransmitted revertively to the sender 103 will have caused the operationof pairs of counting relays No. 9, No. 9 to No. 6, No. 6 inclusive.

As the sequence switch 200 passes into position 5 operating circuitswill-be established for opei ting relays of the register group coinpri.g relays 411 and 415. The first circuit extends from battery onconductor 401, through both windings of relay 411, conductor 412, theright contacts of cam 224, the back contact of the No. 7 counting relayto ground on conductor 221. Until the No. 9 counting relay energizes theright winding of relay 411 is shunted over a circuit from the junctionbetween the windings thereof, over its left contact, conductor 413, theright contacts of cam 225, the back contact of the No. 9 counting relay,to ground on conductor 221. As soon as the No. 9 counting relayenergizes this shunt is opened and relay 411 operates. A second circuitis also closed from battery on conductor 401, through both windings ofrelay 415, conductor 416, the right contacts of cam 226, the backcontact of the No. 6 counting relay, to ground on conductor 221. Untilthe No. 8 counting relay energizes relay 415 is shunted in a circuitextending from the junction point between the windings of relay 415,over the left back contact thereof, conductor 417, the right contacts ofcam 227, the back contact of the No. 8 counting relay to ground onconductor 221. As soon as the No. 8 counting relay energizes this shuntis opened and relay 415 operates. lVhen the No. 7 counting relayoperates the operating circuit of relay 411 is opened at its backcontact and relay 411 deenergises. As soon as the No. 6 counting relayenergizes the circuit of relay 415 is opened at itsback contact. Thuswhen the sequence switch 200 advances into position 6 at the end'of thetransmission of the second series of impulses no relays of the registergroup 411 and 415 remain op erated.

As sequence switch 200 leaves position 5 the locking circuits of theoperated counting relays are opened at the lower left contact of cam 222and as the sequence switch arrives in position 6 relay 210 is againoperated over the pulsing circuit in series with the stepping relay ofthe sender 103. In the manner previously described relay 212 operatesand locks following the operation of relay 210, advancing sequenceswitch 200 into position and thereby including relay 214 in thefundamental circuit. Counting relays of the call indicator and of thesender 103 are thereupon operated and locked in the manner previouslydescribed until the sender 103 is satisfied as to its hundredsregistration when the fundamental circuit is opened at the sender 103 inthe usual manner. Thereupon relays 210 and 214 are deenergized, relay210 unlocking relay 212 which in turn deenergizes advancing sequenceswitch 200 into position 8. Since it has been assumed that the hundredsdigit of the wanted subscribers number is nine, the transfer of theregistration from the sender 103 to the call indicator will haveoperated five pairs of counting relays No. 9, No. 9 to No. 5, No. 5inclusive for the purpose of operating register relays of the groups418, 421 and 424.

Prior to the advance of sequence switch 200 out of position 7 a circuitwill be effective from battery on conductor 401, through both windingsof register relay 418, conductor 419, the right contact of cam 230, thelower right contact of cam 224, the back contact of the No. 7 countingrelay to ground on conductor 221. Until the No. 9 counting relayoperates a shunt exists around the right winding of relay 418 extendingfrom the junction between the windings thereof, over its left backcontact, conductor 420, the right contact of cam 231, the lower rightcontact of cam 225, the back contact of the No. 9 count ing relay, toground on conductor 221. As soon as the No. 9 counting relay operatesthis shunt is opened and relay 418 operates. A circuit is also closedfrom battery on conductor 401, through both windings of relay 421,conductor 422, the right contact of cam 232, the lower right contact ofcam 226, the back contact of the No. 6 counting relay, to ground onconductor 221. Until the No. 8 counting relay operates a shunt existsaround the right winding of relay 421 extending from the junction pointbetween its windings, over the inner left back contact thereof,conduct-or 423, the right contact of cam 233, the lower right contact ofcam 227, the back contact of the No. 8 counting relay to ground onconductor 221. As soon as the No. 8 counting relay operates this shuntis opened and relay 421 operates. A circuit is also established frombattery on conductor 401, through both windings of relay 424, conductor425, the lower right contact of cam 234, the back contact of the No. 3counting relay, to ground on conductor 221, and a shunt around the rightwinding of relay 424 exists from the junction of its windings, over itsleft back contact, conductor 426, the right contacts of cam 229,

the back contact of the No. 5 counting relay,

to ground over conductor 221. This shunt is removed when the No. 5counting relay energizes and relay 424 thereupon operates.

As soon as the No. 7 counting relay energizes the operating circuit ofrelay 418 is opened at the back contact of this counting relay and relay418 releases. The operation of t 1e No. 6 counting relay also opens theoperating circuit of relay 421 and the latter relay releases. Thus atthe end of the third series of impulses relay 424 is the only registerrelay of the group 418, 421and 424 which remains operated. This relaylooks over its inner right front contact, conductor 427, the

lower right contact of cam 235, to ground on conductor 213 as soon assequence switch 200 adx'ances into position 7 When sequence switch 200leaves position 7 the locking circuits for the operated counting relaysare opened at the lower left contact of cam 222, and as the sequenceswitch arrives in position 8 relay 210 is again operated over thepulsing circuit in series with the stepping relay of sender 103. In themanner previously described relay 212 operates and locks following theoperation of relay 210, advancing sequence switch 200 into position 9and thereby including relay 214 in the pulsing circuit. Counting relaysof the call indicator and of the sender 103 are thereupon operated andlocked in the manner previously described until the sender 103 issatisfied as to its tens digit registration when the pulsing circuit isopened at the sender 103. Thereupon relays 210 and 214 deenergize, relay210 unlocking relay 212 which in turn deenergizes advancing sequenceswitch 200 into position 10. Since it has been assumed that the tensdigit of the wanted line number is eight all of the pairs of countingrelays from No. 9, No. 9 to No. 1, No. 1 inclusive will have beenoperated.

Prior to the advance of sequence switch 200 out of position 9 a circuitwill be effective from battery on conductor 401, through both windingsof relay 300, conductor 301, the lower left contact of cam 228, the backcontact of the No. 4 counting relay, to ground on conductor 221. Untilthe No. 9 counting relay operates a shunt exists around the right winding of relay 300 extending from the junction between its windings, theleft back contact of relay 300, conductor 302, upper left and lowerright contacts of cam 225, the back contact of the No. 9 counting relay,to ground over conductor 221. As soon as the No. 9 counting relayoperates this shunt is opened and relay 300 energizes. A circuit is alsoclosed from battery on conductor 401, through both windings of relay303, conductor 304, the lower left contact of cam 234, the back contactof the No. 3 counting relay, to ground on conductor 221. Until the No. 8counting relay operates a shunt exists around the right winding of relay303 extending from the junction between its Windings, over its innerleft back contact, conductor 305, the upper left and lower rightcontacts of cam 227, the back contact of the No. 8 counting relay, toground on conductor 221.

' As soon as the No. 8 counting relay operates 1 relay 306 operates.

relay 306 extending from the junction between the windings thereof, overits inner left back contact, conductor 308, the upper left and lowerright contacts of cam 224, the back contact of the No. 7 counting relay,to ground on conductor 221. As soon as the No. 7 counting relay operatesthis shunt is opened and A circuit may also be traced from battery onconductor 401, through both windings of relay 309, conductor 310, thelower left contact of cam 237, the back contact of the No. 1 countingrelay to ground on conductor 221. Until the No. 6 counting relayoperates a shunt exists around the right winding of relay 309 extendingfrom the junction between the windings thereof, over its inner left backcontact, conductor 311, the upper left and lower right contacts of cam226, the back contact of the No. 6 counting relay, to ground onconductor 221. As soon as the N0. 6 counting relay operates this shuntis opened and relay 309 energizes. Still another circuit may be tracedfrom battery on conductor 401, through both windings of relay 312,conductor 313, the lower left contact of cam 238, the back contact ofthe No. 0 counting relay to ground on conductor 221. Until the No. 5counting relay operates the right winding of relay 312 is shunted in acircuit extending from the junction point between its windings, over itsinner left back contact, conductor 314, the upper left and lower rightcontacts of cam 229, the back contact of the No. 5 counting relay toground on conductor 221. As soon as the No. 5 counting relay operatesthis shunt is removed and relay 312 operates.

hen the N0. 4, No. 3, No. 2 and No. 1 counting relays operated thepreviously traced operating circuit-s for relays 300, 303, 306 and 309were opened at the back contacts of such counting relays and thereforeat the time sequence switch 200 advances out of position 9 into position10 only one register relay, 312', of the tens register remains operated.This relay locks from battery on conductor 401, through both of itswindings and its inner right front contact, conductor 350, the upperleft contact of cam 222 to ground on conductor 213 as soon as sequenceswitch 200 reaches position 9 Upon leaving posi tion 9 the lockingcircuits of all the operated counting relays are opened at the lowerleft contact of 0am 222 in readiness for the registration of the unitsdigit.

Vith sequence switch 200 in position 10 relay 210 is again energizedover the pulsing circuit in series with the stepping relay of the sender103. In the manner previously described relay 212 operates and locksfollowing the operation of relay 2 1 0, advancing sequence switch 200into position 11 thereby including relay 214 in the pulsing circuit.Countingrelays of the call indicator and of the sender 103 are thereuponoperated and locked in the manner previously described until the sender103 is satisfied as to its units registration when the pulsing circuitis opened at the sender 103. hereupon relays 2'10 and 214 deenergize,relay 210 in turn unlocking relay 212 which deenergizes advancingsequence switch 200 into position 12. Since it has been assumed that theunits digit of the Wanted line is three the pairs of counting relays No.9 No. to No. 6, No. 6 inclusive will have been operated.

Prior to the advance of sequence switch 200 out of position 11 a circuitwill be effective from battery on conductor 401, through both windingsof relay 315, conductor 316, the upper right contact of cam 228, theback contactof the No. 4 counting relay, to grount on conductor 221.Until the No. 9 counting relay operates a shunt exists around the rightwinding of relay 315 from the junction be tween its windings, over itsleft back contact, conductor 317, the upper left contact of cam 231, toelower right contact of cam 225, the back contact of the No. 9 countingrelay, to ground on conductor 221. As soon as the No. 9 counting relayoperates this shunt is opened and relay 315 energizes. A circuit is alsoclosed from battery on conductor 401, through both windings of relay313, conductor 319, the upper right contact of cam 234, the back contactof the No. 3 counting relay, to ground on conductor 221. Until the No. 8counting relay operates a shunt exists around the right winding of relay318 extending from the junction between its windings, over its innerleft back contact, conductor 320, the

upper left contact of cam the lower right contact of cam 227, the backcontact of the No. 8 counting relay to ground on conductor 221. As soonas the No. 8 counting relay operates this shunt is opened and relay 318operates.

A circuit is also established from battery on conductor 401, throughboth windings of relay 321, conductor 322, the right contact of cam 236,the back contact of the No. 2 counting relay to ground on conductor 221.Until the No. 7 counting relay operates a shunt exists around the rightwinding of relay 321 extending from the junction between the windingsthereof, over its inner left back contact. conductor 323, the upper leftcontact of cam 230, the lower right contact of cam 224, theback contactof the No. 7 counting relay, to ground on conductor 221. As soon as theNo. 7 counting relay operates this shunt is opened and relay 321operates. A circuit is also extended from battery, over conductor 401,through both windings of relay 324, conductor 325, the right contact ofcam 23?, the back contact of the No. 1 counting relay, to ground onconductor 221. Until the No. 6 counting relay operates a shunt existsaround the right winding of relay 324 extending from the junction of thewindings thereof, over its inner left back contact, conductor 326, theupper left contact of cam 232, the lower'right contact of cam 226, theback contact of the No. 6 counting relay, to ground on conductor 221. Assoon as the No. 6 counting relay operates this shunt is opened and relay324 operates. Still another circuit may be traced from battery onconductor 401, over both windings of relay 327, conductor 328, the rightcontact of cam 238, the back contact of the No. 0 counting relay, toground on conductor221. Until the No. 5 counting relay operates theright winding of relay 327 is shunted in a circuit extending from thejunction between the windin s thereof, over its inner left back contact,conductor 329, the right contact of cam 239, the lower right contact ofcam 229," the back contact of the No. 5 counting relay, to ground onconductor 221. Since it has been assumed that the No. 5 counting relayis not energized this shunt is not opened and relay 327 does notoperate. 7 hen therefore sequence switch 200 advances out of position 11into position 12 only register relays 315, 318, 321 and 324 of the unitsregister remain operated. These relays then lock as soon as sequenceswitch 200 reaches position 11 1 from battery on conductor 401, overboth windings of these relays, the inner right front contact of each,conductor 330, the upper contact of cam 235, to ground on conductor 313.Upon leaving position 11 the locking circuits of all operated countingrelays are opened at the lower left contact of cam 222 and these relaysdeenergize.

WVith sequence switch 200 in position 12 relay 210 is again energizedover the pulsing circuit in series with the stepping relay of the sender103. In the manner previously described relay 212 operates and locks,advancing sequence switch 200 into position 13 thereby including relay214 in the fundamental circuit. Counting relays of the call indicatorand of the sender 103 are thereupon operated and locked in the mannerpreviously described. For the purpose of this description it will beassumed that the stations register of the sender 103 is connected withthe train of counting relays'of such sender in a manner similar to theconnection of the other registers of the sender. When therefore thesender 103 is satisfied as to its stations registrations, which has beenassumed to be for the stations letter J, relays 210 and 214 deenergize,relay 210 in turn unlocking relay 212 which deenergizes, advancingsequence switch 200 into position 14. At this time the pairs of countingrelays No. 9, No. 9 to No. 4, No. 4 inclusive will havebeen operated andlocked.

Prior to the advance of sequence switch 200 out of position 13 a circuitwill be effective from battery on conductor 401, through both windingsof relay 331, conductor 332, the upper left contact of cam 228, the backcontact of the No. 4 counting relay, to ground on conductor 221. Untilthe N o. 9 counting relay operates a shunt exists around the rightwinding of relay 331 extending from the junction between its windings,its left back contact, conductor 333, the lower contact of cam 231, thelower right contact of cam 225, the back contact of the No. 9 countingrelay to ground on conductor 221. As soon as the No. 9 counting relayoperates this shunt is removed and relay 331 operates. A circuit is alsoclosed from battery on conductor 401, through both windings of relay334, conductor 335, the upper left contact of cam 234, the back contactof the No. 3 counting relay, to ground on conductor 221. Until the No. 8counting re- I lay operates a shunt exists around the right winding ofrelay 334 extending from the junction between its windings, over itsinner left front contact, conductor 336, the lower contact of cam 233,the lower right contact of cam 227, the back contact of the No. 8counting relay, to ground on conductor 221. As soon as the No. 8counting relay operates this shunt is opened and relay 334 operates.

A circuit is also established from battery on conductor 401, throughboth windings of relay 337, conductor 338, the upper left contact of cam236, the back contact of the No. 2 counting relay to ground on conductor221. Until the No. 7 counting relay operates a shunt exists around theright winding of relay 337 extending from the junction between itswindings, its inner left back contact, conductor 339, the lower contactof cam 230, the lower right contact of cam 224, the back contact of theN0. 7 counting relay to ground on conductor 221. As soon as the No. 7counting relay operates this shunt is opened and relay 337 operates. Acircuit may also be traced from' battery on conductor 401, through bothwindings of relay 340, conductor 341, the upper left contactof cam 237,the back contact of the No. 1 counting relay, to ground on conductor221. Until the No. 6 counting relay operates a shunt exists around theright winding of relay 340 extending from the junction between itswindings, over its inner left back contact, conductor 342, the lowercontact of cam 232, the lower right contact of cam 226, the back contactof the No. 6 counting relay, to ground on conductor 221. As soon as theNo. 6 counting relay operates this shunt is removed and relay 340energizes. Still another circuit may be traced from battery on conductor401, throughboth windings of relay 343, conductor 344, the upper leftcontact of cam 238, the back contact of the No. 0 counting relay toground on conductor 221. Until the No. 5 counting relay operates a shuntexists around the right winding of relay 343 extending from the junctionbetween its windings, over its inner left back contact, conductor 345,the left contact of cam 239, the

lower right contact of cam 229, the back contact of the No. 5 countingrelay to ground on conductor 221. soon as the N o. 5 counting relayoperates this shunt is opened and relay 342 operates.

WVhen the No. 4 counting relay operates the energizing circuit of relay331 is opened and that relay releases. When therefore sequence switch200 advances out of position 13 into position 14, register relays 334,337, 340 and 343 of the stations register remain operated. These relaysthen look as soon as sequence switch 200 reaches position 13 frombattery on conductor 401, over both windings of each of these relays,the inner right front contact of each relay, conductor 346, to ground onconductor 213, over the lower left contact of cam 2355. Upon leavingposition 13 the locking circuits of all operated counting relays areopened at the lower left contact of cam 222 and these relays deenergize.

When sequence switch 200 reaches position 14 a circuit is establishedfor relay 240 extending from battery, through the winding of relay 240to ground over the left contact of cam 241. The previously tracedcircuit for relay 208 is opened at the upper left contact of cam 209 andrelay 208 releases as soon as sequence switch 200 leaves position 13.The previously traced circuit between the sender 103 and the callindicator is now established but battery is now connected through thewinding of relay 210 and the right contact of relay 240 to conductor 125rather than over the left contact of relay 208 to conductor 124,

and ground is connected from conductor 213,

over the lower right contact of 0am 211 and the left contact of relay240 to conductor 124 rather than over the right contact of relay 208 toconductor 125. This reversal of the connection of battery and ground tothe pulsing circuit now operates in the wellknown manner to advance thesender 103 into the talking selection position whereupon the districtselector circuit is prepared for talking and the sender 103 becomesdismissed. The

talking circuit at the district selector 104 is now established from thetip brush over the upper contact of cam 112, upper right winding of therepeating coil, the winding of polarized relay 127, the lower rightwinding of the repeating coil, lower contact of cam 111 to the ringbrush of the district selector.

At the call indicator, relay 210 energizes over the pulsing circuit inturn operating re-' 210 deenergizes in turn releasing relay 212 which,upon deenergizing, closes a circuit from ground at its right backcontact, over the lower left contact of cam 206 for advancing sequenceswitch 200 into position 18.

At the time sequence switch 200 reached position 7 a circuit wasestablished for relay 242, over the lower right contact of cam 235 inparallel with the locking circuit of the register relay 424. A circuitis thereupon effective for lighting the N0. 3 thousands lamp 429extending from ground at the contact of relay 242, conductor 243, theright back contact of register relay 410, the outer right frontcontactof register relay 400, the outer left front contact of relay 405,the No. 3 thousands lamp 429, the next to innermost back contact ofrelay 430 to battery on conductor 401. A circuit is also establishedfrom ground at the outer right front contact of register relay 424,through the No. 9 hundreds lamp 445,

the outer right back contact of relay 431 to WVhen sequencebattery onconductor 401. switch 200 arrived in position 9 a circuit wasestablished for relay 244, over the upper left contact of cam 222 inparallel with the locking circuit of register relay 312. A circuit isthereupon effective for lighting the No. 8 tens lamp 347 which may betraced from ground at the contact of relay 244, conductor 245, the outerright back contact of register relay 300, the outer left front contactof relay 312, outer left back contact of relay 309 to battery, throughthe lamp 347. As soon as sequence switch 200 arrives in position 16 acircuit is established for relay 246 extending from ground through thewinding of that relay to battery over the upper right contact of cam209. l/Vith relay 246 operated circuits are established for lighting theNo. 3 units lamp 348 and the J stations lamp 349. The circuit of lamp348 may be traced from ground at the outer contact of relay 246,conductor 247, the outer right front contact of register relay 315, theouter right front contact of relay 318, the outer right front contact ofrelay 321, the outer right front contact of relay 324, the outer rightback contact of relay 327 to battery, through lamp 348. The circuit oflamp 349 may be traced from ground at the inner contact of relay 246,over conductor 248, the outer right back contact of register relay 331,the outer left front contact of relay 343, the outer left front contactof relay 340, the outer left front contact of relay 337, the outer leftfront contact of relay 334 to battery through lamp 349. Lamps 445, 429,347, 348 and 349 have now lighted to display the number of the wantedline 3983-J.

At this point it Will be advantageous to explain how translation iseffected between the register relays of Fig. 4 to light the otherthousands and hundreds lamps to display thousands and hundreds digitsdialed by a calling subscriber. In the setting of the reg ister relays400, 405, and 410 in accordance with the thousands digit registered bythe calling subscriber in the sender 103, five registration combinationsmay be effected by these register relays as follows: For digits 0 and 1relay 400 is energized alone, for digits 2 and relays 400 and 405 areboth energized, for digits 4 and 5 relay 405 is energized alone, fordigits 6 and 7 no relays areoperated, and for digits 8 and 9 relay 410is operated alone. The thousands lamps are arranged in pairs, the No. 0and No. 1 lamps, the No. 2 and N0. 3 lamps, etc. being paired, andconductors being extended from the junction between the lamps of eachpair to contacts of the register relays in such a manner that each ofthe registration conditions above enumerated is effective to extend anoperating circuit to either one of a particular pair of lamps.

Register relays 411 and 415 are operated in accordance with thethousands digit dialed and also in accordance with the hundreds digitdialed. For example, if the thousands digit is even and the hundredsdigit is less than 5, register relay 411 only will be operated. If thethousands digit is even and the hundreds digit is greater than 4,register relays 411 and 415 will both be operated. If the thousandsdigit is odd and the hundreds digit is less than 5, only register relay415 will be operated and if the thousands digit is odd and the hundredsdigit is greater than 4, both relays 411 and 415 will be unoperated. Byan inspection of Fig. 4 of the drawings it will be noted that whenever aregistration condition is set up on relays 411 and 415, denoting an eventhousands digit, relay 430 operates but that this relay does not operateif the thousands digit is odd. Also if the registration conditionindicates that the hundreds digit is less than 5, relay 431 operates butthat this latter relay does not operate if the hundreds digit is greaterthan 4. Thus when the thousands digit is even and relay 430 is operatedthe even numbered lamp of a pair selected by the register relays 400,405 and 410 is selected over a front contact of relay 430 and when thethousands digit is odd and relay 430 is not operated the odd numberedlamp-of a pair isselected over a back contact of relay 430.

In the setting of the register relays of the group 418, 421 and 424 inaccordance with the hundreds digit registered in the sender 103, fiveregistration combinations may be effected. For digits 0 and 5 relay 418only is operated. For digits 1 and 6 relays 418 and 421 are operatedtogether, for digits 2 and 7 only relay 421 is operated, and for digits4 and 9 relay 424 only is operated. The hundreds lamps are arranged inpairs, the No. 0 and No. 5 lamps, the No. 1 and N0. 6 lamps, etc., beingpaired and conductors being extended from the junction between the lampsof each pair to contactsof the register relays in such a manner thateach of the registration conditions, just enumerated, is effective toextend an operating circuit to either one a of a particular pair oflamps. As previously stated relay 431 always operates when the hundredsdigit is less than 5, and it therefore follows that when relay 431operates the lamp of a pair selected by the register relays 418, 421 and424, which bears a number less than 5, is selected over the frontcontact of relay 431, and that with relay 431 unoperated the lamp of thepair selected by relays 418, 421 and 424, which bears a number greaterthan 4, is selected.

Resuming the description of the operation of the circuits for theassumed call to the wanted line 150, when sequence switch 200 reachedposition 16 following the completion of the registration, a circuit wasestablished for relay 204, from battery, through the winding of thatrelay, the back contact of relay 205, to ground at the right contact ofcam 241. Relay 204 becomes energized and opens the circuit of relay 110which in turn deenergizes and disconnects the incoming conductors oftrunk 106 from conductors 124 and .125 and extends such incomingconductors, through the windings of relay 108. If at this time thetalking circuit has been completed at the district selector 104 thenrelay 108 energizes in series with the polarized relay 127, but relay127 does not energize. Relay 108 upon energizing now closes a holdingcircuit for relay 114 and shunts down relay 121.

The operator at the manual office, noting the display of the wanted linenumber, plugs into the jack of the wanted line completing a circuit fromground on the sleeve of jack 128, over the sleeveof plug 107, throughthe winding of relay 120, outer right back contact of relay 121, theouter right front contact of relay 114, the back contact of relay 129,the back contact of relay 130, to battery through the winding of relay131. Relays 120 and 131 energize in this circuit. Relay 120 at itsintermediate lower back contact opens the circuit of relay 115 whichdeenergizes and in turn opens the interrupting circuit of lamp 116. Atits lowermost back contact relay 120 opens the circuit of relays 118 and201. Relay 201 deenergizes removing ground from conductor 213 therebyreleasing all operated register relays of the call indicator andextinguishing the lamps lighted thereby. At its left back contact relay201 closes a circuit extending from ground thereat, over the upper rightcontact of cam 206 to battery, through the winding of sequence switch200 for advancing such sequence switch into normal position. Operatedcontrol relays of the call indicator are thereupon released and the callindicator is restored for use on another call,

lVith relays 120 and 131 energized a circuit 1 responds relay 129operates, removing at its back contact the shunt around the winding ofrelay 130, which thereupon becomes energized. Relay 130 now closes acircuit from battery, through its right front contact, through itswinding, thence through the winding of relay 120 to ground on the sleeveof jack 128 as previously traced, thus shunting relay 131 whichthereupon deenergizes disconnecting ground and the ringing currentsource from the tip and ring of plug 107, and connecting the rightwindings of repeating coil 135 to the plug. Supervisory relay 134 nowenergizes over the called line and closes a circuit for reversing relay109, extending from battery, through the winding of such relay, thefront contact of relay 134, to ground at the left front contact of relay130. Relay 109 upon energizing reverses the direction of current flowingover the connection extending back to the district trunk 102 forsupervisory or call charging purposes. The subscribers are now connectedinto a talking connection, the calling subscriber receiving talkingbattery from the left windings of the repeating coil in the districttrunk and the called subscriber receiving talking current through theright winding of repeating coil 135.

Upon the termination of the conversation the subscribers restore theirreceivers to the switchhooks, the restoration of the calling subscribersreceiver restoring the selectors in the originating oflice in the wellknown manner, and the restoration of the called subscribers receiverrestoring relays 134 and 109. Following the release of the officeselector 105 the circuit of relay 108 is opened, which in turn releasesrelay 114. The release of relay 114 now opens the shunt around thedisconnect lamp 136 which now lights in serieswith relay 120. Theoperator, noting the illumination of lamp 136, withdraws plug 107 fromack 128 whereupon the remaining operated relays of the incoming trunk106 release.

Vhat is claimed is:

1. In a telephone exchange system, a sending device having registersassociated therewith for registering the designation of a wanted line,mechanism for displaying the number of a wanted line, means forcontrolling said mechanism comprising a plurality of registers, andmeans for transferring said designation from the registers of saidsending device to the registers of said controlling means by means ofimpulses revertively transmitted from said controlling means to saidsending device.

2. In a telephone exchange system, a sending device having registersassociated there with for registering the designation of a wanted line,lamps for displaying the number of a wanted line, means for controllingsaid lamps comprising a plurality of registers, and means fortransferring said designation from the registers of said sending deviceto the registers of said controlling means by means of impulsesrevertively transmitted from said controlling means to said sendingmeans.

3. In a telephone exchange system, a sending device having registersassociated therewith for registering the designation of a wanted line,lamps for displaying the number of a Wanted line, means for controllingsaid lamps comprising a plurality of registers and means fortransferring said designation from the registers of said sending deviceto the registers of said controlling means comprising means forrevertively transmitting trains of impulses to said sending device fromsaid controlling means, means for counting the impulses in each train sotransmitted, and means for operating the registers of said controllingmeans in accordance With the operation of said counting means.

4:. In a multi-oitice telephone exchange system, calling and calledlines, an operators position, a trunk line, means including said trunkline for extending a calling line to said position, means forautomatically indicating the number of a called line at said position,means for revertively sending trains of impulses over the trunk line,and means responsive to said impulses to control said indicating means.

5. In a telephone system, a sending device having registers associatedtherewith for registering the designation of a wanted line, a callindicator comprising a bank of lamps for displaying each digit of thewanted line number, a greater number of registers than there are banksof lamps, and translating means for selectively lighting lamps of saidbanks under the control of said latter registers, and means fortransferring said designation from the registers of said sending deviceto the registers of said call indicator by means of impulses revertivelytransmitted from said call indicator to said sending device.

6. In a telephone system, a sending device having registers associatedtherewith for registering the designation of a wanted line, there beinga register for registering each digit of a designation, a call indicatorcomprising a bank of lamps for displaying each digit of a wanted linenumber, a greater number of registers than there are banks of lamps andtranslating means for selectively lighting lamps of said banks under thecontrol of said latter registers, and means for transferring saiddesignation from the registers of said sending deviceto the registers ofsaid call indicator comprising means for revertively transmitting anumber of trains of impulses to said sending device from said callindicator equal to the number of registers in said call indicator andgreater than the number of registers in said sending device.

7. In a telephone system, a sending device having registers associatedtherewith for registering the'digits of a wanted line designation, therebeing a register for registering each digit, a call indicator comprisinga bank of lamps for displaying each digit of a wanted line number, agreater number of registers than there are digits to be registered, andtranslating means for lighting certain of said banks of lamps under thejoint control of a plurality of said latter registers, and means fortransferring said designation from the registers of said sending deviceto the registers of said call indicator comprising means for revertivelytransmitting a number of trains of impulses to said sending device fromsaid call indicator.

In witness whereof, I hereunto subscribe my name, this th day of June,1928.

EDGAR H. CLARK.

